ObjectiveTo evaluate the blocking effect and mechanism of Soybeanderived BowmanBirk inhibitor (BBI) on LPSmediated downregulation for tight junction protein(HT29 cells) in intestinal epithelial cells(IECs).MethodsThe toxic effect of LPS and BBI on HT29 cells was detected by CCK8 Kit. HT29 cells were pretreated by BBI for 6 hours prior to LPS stimulation, the expression of tight junction protein (ZO1 and Occludin), TLR4, and MyDD8 was detected by the quantitative realtime polymerase chain reaction (PCR) and Western Blot; activation of NFκB was measured by Western Blot.ResultsLPS (1 000ng/mL) and BBI (1 000μg/mL) showed no cytotoxicity on HT29 cells. LPS could significantly upregulate the expression of TLR4 in HT29 cells, the upregulation had timedose effect, and could significantly downregulate the expression of tight junction protein, the downregulation effect was directly proportional to the concentration of LPS, could activate NFκB, and had dose effect, effect of LPS on HT29 cells could be significantly inhibited by BBI.ConclusionBy inhibiting the expression of TLR4 and activation of NFκB in IECs induced by LPS, BBI can significantly block the LPSmediated inhibitory effect on tight junction protein in intestinal epithelial cells.